TFOS DEWS II pathophysiology report

Age-related Autoimmune Changes in Lacrimal Glands

Aging is a complex process associated with dysregulation of the immune system and low levels of inflammation, often associated with the onset of many pathologies. The lacrimal gland (LG) plays a vital role in the maintenance of ocular physiology and changes related to aging directly affect eye diseases. The dysregulation of the immune system in aging leads to quantitative and qualitative changes in antibodies and cytokines. While there is a gradual decline of the immune system, there is an increase in autoimmunity, with a reciprocal pathway between low levels of inflammation and aging mechanisms. Elderly C57BL/6J mice spontaneously show LGs infiltration that is characterized by Th1 but not Th17 cells. The aging of the LG is related to functional alterations, reduced innervation and decreased secretory activities. Lymphocytic infiltration, destruction, and atrophy of glandular parenchyma, ductal dilatation, and secretion of inflammatory mediators modify the volume and composition of tears. Oxidative stress, the capacity to metabolize and eliminate toxic substances decreased in aging, is also associated with the reduction of LG functionality and the pathogenesis of autoimmune diseases. Although further studies are required for a better understanding of autoimmunity and aging of the LG, we described anatomic and immunology aspects that have been described so far.

Translational Preclinical Pharmacologic Disease Models for Ophthalmic Drug Development

Preclinical models of human diseases are critical to our understanding of disease etiology, pathology, and progression and enable the development of effective treatments. An ideal model of human disease should capture anatomical features and pathophysiological mechanisms, mimic the progression pattern, and should be amenable to evaluating translational endpoints and treatment approaches. Preclinical animal models have been developed for a variety of human ophthalmological diseases to mirror disease mechanisms, location of the affected region in the eye and severity. These models offer clues to aid in our fundamental understanding of disease pathogenesis and enable progression of new therapies to clinical development by providing an opportunity to gain proof of concept (POC). Here, we review preclinical animal models associated with development of new therapies for diseases of the ocular surface, glaucoma, presbyopia, and retinal diseases, including diabetic retinopathy and age-related macular degeneration (AMD). We have focused on summarizing the models critical to new drug development and described the translational features of the models that contributed to our understanding of disease pathogenesis and establishment of preclinical POC.

Emerging targets of inflammation and tear secretion in dry eye disease

The underlying mechanisms of dry eye are thought to be part of a vicious circle involving a hyperosmolarity-triggered inflammatory cascade, resulting in loss of goblet cells and glycocalyx mucin and observed corneal and conjunctival epithelial cell damage. This damage leads to increased tear film instability, further hyperosmolarity and hence perpetuating of a vicious circle. The aim of dry eye management is to restore the homeostasis of the tear film and break the perpetuation of this vicious circle. Despite the plethora of treatment options available, many of these are largely palliative, short-lived and require repeated instillations. Two emerging areas in dry eye therapy aim to promote tear secretion and to safely manage dry eye-associated inflammation and are the focus of this review.

Comparison of Meibomian Gland Imaging Findings and Lipid Layer Thickness between Primary Sjögren Syndrome and Non-Sjögren Syndrome Dry Eyes

Purpose: To compare meibomian gland (MG) imaging findings and lipid layer thickness (LLT) between patients with primary Sjögren syndrome (SS) dry eyes (DE) and non-SS DE.Methods: A total of 60 patients-30 with SS DE and 30 with non-SS DE were evaluated. Infrared image findings of MGs and LLT were assessed using the LipiView II interferometer.Results: The maximum LLT was significantly lower in the SS DE group. SS DE exhibited significantly higher MG dropout compared to the non-SS DE. Average and maximal LLT showed significant negative correlations with MG dropout in both groups (p<0.05). Conjunctival staining scores showed significant correlations with average and maximum LLT and MG dropout values in the SS DE group (p<0.05).Conclusion: These findings suggest that the new interferometer will be useful in understanding the pathophysiology of SS DE.

Vitamin D Enhances the Efficacy of Topical Artificial Tears in Patients With Dry Eye Disease

PURPOSE

To investigate the efficacy of topical carbomer-based lipid-containing artificial tears (CLAT) and hyaluronate (HU) in patients with dry eye disease (DED) based on serum 25-hydroxyvitamin D (25HD) levels and cholecalciferol (vitamin D) supplementation.

METHODS

A total of 116 patients with DED from June 2015 to June 2016 were included. The participants were divided into the vitamin D deficiency (VDD) group and the non-VDD group according to their serum 25HD levels. The patients determined the ways of cholecalciferol supplementation. Ocular Surface Disease Index (OSDI) score, visual analog pain scale score, lid hyperemia, tear breakup time (TBUT), corneal fluorescein staining score, and Schirmer test were compared between baseline and 2 weeks posttreatment after topical applications and between before and after cholecalciferol supplementation.

RESULTS

The OSDI and visual analog pain scale scores of both VDD and non-VDD groups decreased after application of topical CLAT and HU compared with baseline values (P < 0.05 for all, paired t test). TBUT, corneal fluorescein staining score, and lid hyperemia in the VDD group remained unaffected by topical CLAT and HU, whereas those in the non-VDD group were improved (3.2 ± 1.7 vs. 4.1 ± 2.2, 0.5 ± 0.7 vs. 0.4 ± 0.6, and 2.2 ± 0.8 vs. 1.9 ± 0.7 in the non-VDD group, P = 0.001, 0.030, and 0.012, respectively). OSDI score, TBUT, and lid margin hyperemia were improved in the intramuscular group after cholecalciferol supplementation compared with pretreatment (33.2 ± 23.2 vs. 28.5 ± 21.9, 3.5 ± 1.9 vs. 6.0 ± 2.5, and 2.2 ± 0.7 vs. 1.2 ± 0.8, P < 0.05, Wilcoxon rank test).

CONCLUSIONS

The effect of topical CLAT and HU was dependent on serum 25HD levels. Cholecalciferol supplementation enhanced the efficacy of topical treatment and may be a useful adjuvant therapy for patients with DED refractory to topical lubricants.

Comorbidities and Prescribed Medications in Patients With or Without Dry Eye Disease: A Population-Based Study

PURPOSE

To assess the proportion of comorbidities in patients with dry eye disease (DED) compared with matched patients without DED in a comprehensive US population.

DESIGN

Retrospective case-control study.

METHODS

Healthcare records for insurance claims data, detailing medical services incurred by military personnel and their families and dependents in military and civilian facilities across the United States from January 1, 2003, to March 31, 2015, were obtained from the Department of Defense (DOD) Military Health System (MHS). Diagnostic and procedural codes related to DED from selected International Classification of Diseases, Ninth Revision (ICD-9) Current Procedural Terminology codes and prescriptions for cyclosporine A ophthalmic emulsion were used to identify patients with newly diagnosed and prevalent DED in the MHS database. Age, sex, and geographically matched patients without DED were also identified from healthcare claims records. Medication use and comorbidities in these patient populations were assessed and compared.

RESULTS

In both the newly diagnosed and prevalent DED samples, the most common comorbidities were hypertension, cataracts, thyroid disease, type 2 diabetes, and glaucoma. All comorbidities were significantly higher in the DED vs non-DED groups (P < .001). Medication use (including, but not limited to, ophthalmic agents and drugs to treat comorbidities) was also significantly higher in the DED than in the non-DED groups (P < .001).

CONCLUSIONS

The high proportions of patients with DED with a range of comorbidities and prescribed medications highlight the need for a multidisciplinary approach to the management of these patients.

Dry Eye Disease: Consideration for Women's Health

Dry eye disease (DED) is a multifactorial disorder of the ocular surface and tear homeostasis that can result in discomfort, pain, and visual disturbance. Untreated, DED can become chronic, progressive, and significantly affect an individual's quality of life. Women are disproportionately affected by DED, are diagnosed at a younger age, and experience more severe symptoms compared with men. DED is associated with a wide range of comorbid conditions; there is a strong association between DED and autoimmune disorders, especially those that affect women at many times the rate of men. Treatment response questionnaires indicate women respond better to a wellness model of treatment for DED than men. Furthermore, women's health care-seeking behaviors provide opportunities for general practitioners, specialists, and women's health centers to help identify women with DED or at risk for DED for referral to an eye care specialist. This review of the prevalence of DED in women, and gender and sex-specific aspects of DED, highlight a significant opportunity for action. Earlier diagnosis and treatment of this common but burdensome condition could significantly improve a woman's quality of life.

High-Mobility Group Box 1 in Dry Eye Inflammation

Purpose

To determine high-mobility group box 1 (HMGB1) expression during experimental dry eye (EDE) and dry eye-like culture conditions and elucidate its role in corneal dry eye-related inflammation.

Methods

EDE was induced in 8- to 12-week-old C57BL/6 mice. Corneal tissue sections and lysates from EDE and untreated mice were evaluated for HMGB1 expression by immunostaining and quantitative real-time PCR (qPCR). For in vitro studies, human corneal epithelial cells (HCEC) were treated with hyperosmolar media, toll-like receptor (TLR) agonists, or proinflammatory cytokines to determine HMGB1 expression. HCEC were also treated with human recombinant HMGB1 (hrHMGB1) alone or in combination with inflammatory stimuli, and TNFα, IL-6, and IL-8 expression evaluated by qPCR and ELISA. Nuclear factor-κB (NF-κB) p65 nuclear translocation was determined by immunostaining.

Results

EDE mice had higher corneal HMGB1 RNA and protein expression compared to untreated animals. In HCEC, hyperosmolar stress and TNFα treatment stimulated HMGB1 production and secretion into culture supernatants. However, in vitro stimulation with hrHMGB1 did not induce secretion of TNFα, IL-6, or IL-8 or NF-κB p65 nuclear translocation. In addition, the inflammatory response elicited by TLR agonists fibroblast-stimulating lipopeptide-1 and lipopolysaccharide was not enhanced by hrHMGB1 treatment.

Conclusions

HMGB1 expression was enhanced by dry eye conditions in vivo as well as in vitro, during hyperosmolar stress and cytokine exposure, suggesting an important role for HMGB1 in dry eye disease. However, no direct inflammatory effect was observed with HMGB1 treatment. Therefore, under these conditions, HMGB1 does not contribute directly to dry eye-induced inflammation and its function at the ocular surface needs to be explored further.

Clinical Correlations of Novel Autoantibodies in Patients with Dry Eye

Background

Diagnostic criteria for Sjögren's syndrome (SS) are continually being updated in pursuit of more precise and earlier diagnosis to prevent its complications. Owing to the high rate of false negative traditional serological markers, the need for better serological testing remains.

Objective

To investigate the clinical significance of three recently discovered novel autoantibodies, anti-salivary gland protein 1 (SP1), anti-carbonic anhydrase 6 (CA6), and anti-parotid secretory protein (PSP), in a cohort of dry eye patients with suspected underlying inflammatory/autoimmune disease.

Methods

Medical records of 136 patients with a primary diagnosis of dry eye who underwent laboratory testing between April 2014 and July 2017 were reviewed retrospectively. Data regarding demographic information, ocular and systemic symptoms, previous medical diagnoses, serological test results, and minor salivary gland biopsy results were collected. Dry eye evaluations included tear osmolarity, Schirmer test without anesthesia, conjunctival lissamine green staining, and corneal fluorescein staining in the order listed here.

Results

Of the 136 patients, 9 (9/136, 6.6%) presented with a history of SS, and 9 additional patients (9/127, 7%) received a new diagnosis of SS as a result of evaluations. Fifty-six patients (56/136, 41%) tested positive for at least one of the novel autoantibodies. Fifty-four percent (6/11) of patients with primary SS who underwent the novel serological testing had a positive anti-PSP. Of those, 2 (2/11, 18%) had negative traditional serology and had to undergo minor salivary gland biopsy for definitive diagnosis. Anti-CA6 was associated with increased corneal and conjunctival staining after adjusting for age, sex, and other serologic markers (HR = 1.5, 95% CI = 1.20-1.97, and p = 0.009 and HR = 1.4, 95% CI = 1.04-1.76, and p = 0.02, respectively).

Conclusions

This cross-sectional study demonstrated that anti-CA6 is seen in patients with severe aqueous-deficient dry eye. Whether these patients have an early stage of SS or a different type of autoimmune condition may be determined through longitudinal studies.

Classifying signs and symptoms of dry eye disease according to underlying mechanism via the Delphi method: the DIDACTIC study

Background/aims

Dry eye disease (DED) is categorised by pathophysiology as aqueous deficient dry eye (ADDE), evaporative dry eye (EDE) or mixed. Treatment should be tailored to DED pathophysiology, but this is challenging to determine. This Delphi consultation aimed to categorise and weight signs and symptoms to help identify the evaporative or aqueous deficient DED origin.

Methods

A panel of French DED experts created an initial list of 77 DED signs and symptoms. In a Delphi consultation, experts categorised items by DED pathophysiology. Likert scoring was used to indicate whether items were strongly or moderately indicative of ADDE or EDE. Items could also be judged non-applicable to DED, with the opportunity to suggest alternative diagnoses.

Results

Experts attributed 19 items (of which 11 were strongly indicative) to a pathophysiology of EDE and 12 items (of which four were strongly indicative) to ADDE. Items scored strongly indicative with agreement >90% for EDE were previous chalazia, rosacea/rhinophyma, telangiectasias of eyelid margin and thick non-expressible meibomian gland secretions, and for ADDE were Sjögren syndrome or associated disease, and Schirmer <5 mm after 5 min (without anaesthesia). Seventeen items indicated neither pathophysiology and 18 items were found to be suggestive of alternative diagnoses.

Conclusions

This Delphi consultation categorised signs and symptoms, using an innovative weighting system to identify DED pathophysiology. An algorithm integrating the weighting of each sign and symptom of an individual patient would be valuable to help general ophthalmologists to classify the DED subtype and tailor treatment to DED underlying mechanism.

Subconjunctival injection of mesenchymal stromal cells protects the cornea in an experimental model of GVHD

PURPOSE

To evaluate the therapeutic effect of subconjunctival injection of human mesenchymal stromal cells (hMSCs) in the cornea of mice with graft versus host disease (GVHD).

METHODS

GVHD was induced in mice after hematopoietic stem cell transplantation (HSCT) between MHC-mismatched mouse strains. Subconjunctival injection of hMSCs was applied at day 10 post-HSCT. Infiltration of CD3⁺ cells in the cornea and epithelial alterations were analyzed by immunofluorescence. Tear was assessed using the PRT test and TearLab Osmolarity System. qPCR was used to evaluate changes in cytokines, Pax6 and Sprr1b expression. To evaluate the effect of irradiation, we analyzed the expression of these genes in TBI mice.

RESULTS

Immune cell invasion occurs in mice with GVHD, as shown by the presence of CD3⁺ cells in the cornea. Interestingly, eyes treated with hMSC did not present CD3⁺ cells. Tear osmolarity was increased in GVHD eyes, but not in treated eyes. TNFa expression was highly increased in all corneas except in Control and treated eyes. Pax6 in corneal epithelium showed a similar pattern in GVHD and Control mice, and its gene expression was enhanced in GVHD corneas. In contrast, Pax6 was reduced in GVHD + MSC corneas. We also found an increase in SPRR1B staining in GVHD eyes that was lower in GVHD + MSC mice, demonstrating that corneal keratinization is less frequent after treatment with hMSC.

CONCLUSIONS

The treatment with hMSCs by subconjunctival injection is effective in reducing corneal inflammation and squamous metaplasia in ocular GVHD (oGVHD). Local treatment with hMSCs is a promising strategy for oGVHD.

Ocular Manifestations of Rheumatoid Arthritis: Implications of Recent Clinical Trials

While rheumatoid arthritis (RA) typically presents with synovitis of the small and medium joints of the hands, ocular manifestations of the disease are generally overlooked and largely underdiagnosed. These complications usually present in longstanding RA population and occasionally represents the first manifestation of the disease and generally affect the anterior chamber of the eye, leading to keratoconjunctivitis sicca, episcleritis, scleritis, peripheral ulcerative keratitis and anterior uveitis. In this review, we present the current understanding of the pathophysiologic mechanisms for ocular disease in RA, including the role of oxidative stress, cytokine imbalance, chronic inflammation, vascular permeability, immune complex deposition and the role of T-cells as well as the contribution of tear hyperosmolarity among other factors. We also discuss the clinical presentation and diagnosis of each of the ocular disease entities highlighting the latest strategies in the management of this serious disorders that could potentially lead to blindness and the implications of recently completed and ongoing clinical trials in the field. While RA disease control is the cornerstone in the management of RA-associated ocular manifestations, early recognition of ocular pathology with prompt referral to ophthalmology is of paramount importance in order to prevent blindness and improve the quality of life in this patient population.

Efficacy and safety of 0.1% ciclosporin A cationic emulsion in dry eye disease: a pooled analysis of two double-masked, randomised, vehicle-controlled phase III clinical studies

BACKGROUND/AIM

To assess the treatment effect of 0.1% ciclosporin A cationic emulsion (CsA CE) versus vehicle on signs/symptoms of dry eye disease (DED) in various subgroups (moderate-to-severe DED/severe DED/Sjögren's syndrome (SS)/SS with severe DED).

METHODS

Pooled data were analysed from two similar phase III studies: SICCANOVE (moderate-to-severe DED) and SANSIKA (severe DED with severe keratitis). In both studies, patients aged ≥18 years received CsA CE 0.1% (n=395) or vehicle (n=339) once daily for 6 months. A composite responder efficacy endpoint (corneal fluorescein staining-Ocular Surface Disease Index (CFS-OSDI) at month 6) was used to evaluate the efficacy of CsA CE in alleviating signs/symptoms of DED (response defined as improvement of ≥2 grades in CFS and ≥30% in OSDI (baseline to month 6)). Human leucocyte antigen-DR (HLA-DR) conjunctival expression was used as a biomarker of ocular surface inflammation.

RESULTS

CsA CE-treated patients were significantly more likely to be CFS-OSDI responders than vehicle-treated patients in the overall (OR 1.66, 95% CI 1.11 to 2.50; P=0.015), severe DED (1.80, 1.04 to 3.19; P=0.038) and SS with severe DED (3.37, 1.20 to 11.19; P=0.030) populations. The difference was not significant for CsA CE versus vehicle for the overall Sjögren's population (OR 1.77, CI 0.89 to 3.66; P=0.109). CsA CE also significantly reduced median HLA-DR expression versus vehicle at 6 months (P=0.002).

CONCLUSION

Pooled phase III data indicate CsA CE produced significant improvement in signs/symptoms versus vehicle in patients with moderate-to-severe DED (especially in those with severe keratitis), including patients with SS with severe DED.

Risk factors for ocular surface damage in Mexican patients with dry eye disease: a population-based study

PURPOSE

To analyze potential risk factors for ocular surface damage in a representative population of Mexican patients with dry eye disease (DED).

PATIENTS AND METHODS

A prospective and cross-sectional population-based epidemiologic cohort study was conducted through a survey of patients with symptoms, signs, known preexisting diagnosis, and clinical conditions related to DED. Fluorescein staining, tear break-up time (TBUT), and Oxford lissamine green staining were performed on both eyes of patients enrolled in the study.

RESULTS

A total of 2,725 surveys including 1,543 (56.6%) women and 1,182 (43.3%) men were analyzed. Most common pre-existing diagnosis included dry eye (58%), chronic blepharitis (17%), and ocular allergy (15%). More than 70% of patients had a positive fluorescein test, and this prevalence increased proportionally to the number of reasons for consultation. The same was true for gender (P<0.001) and age (P<0.0001), with women showing a strong correlation with age (R2=0.93912, P=0.001). The association between positive fluorescein staining and diagnosis was significant for dry eye (P<0.0001), Sjögren's syndrome (P<0.0001), and glaucoma (P<0.05). No significant association between TBUT and age or gender was found, but the shorter the TBUT, the larger the prevalence of fluorescein staining. Reduced TBUT was seen more frequently in patients with dry eye (57%), ocular allergy (16%), and chronic blepharitis (15%). Most patients (39%) with Oxford grades III and IV were older, complained of red eye (51.0%), foreign body sensation (47.0%), burning (46.0%), and were using eye drops (67%) and systemic medications (47%).

CONCLUSION

The Mexican profile of patients with significant ocular surface damage related to DED includes women at older ages, complaining of red eye, foreign body, and burning sensation. Diagnoses of dry eye, Sjögren's syndrome, and glaucoma were also risk factors for significant ocular surface damage, along with long-term use of preserved eyes drops and systemic medications.

What's new in dry eye disease diagnosis? Current advances and challenges

Dry eye disease (DED) is a commonly encountered condition in general ophthalmology practice and imparts a significant socioeconomic burden. Despite its prevalence, there remain challenges regarding its diagnosis and management. A major reason behind these challenges is the fact that DED represents an umbrella term that encompasses many different underlying conditions and pathophysiological mechanisms. The purpose of this article is to highlight aspects of DED pathophysiology and focus on targeted diagnostic and therapeutic approaches to this multifactorial, chronic condition.

Efficacy and safety of glycyrrhizin 2.5% eye drops in the treatment of moderate dry eye disease: results from a prospective, open-label pilot study

Background

Dry eye disease (DED) is characterized by a loss of homeostasis of the tear film. It goes along with ocular symptoms, in which ocular surface inflammation and damage play etiological roles. High-mobility group box 1 protein (HMGB1) is a pro-inflammatory protein found in the tear fluid during conjunctivitis, blepharitis and DED. Glycyrrhizin binds to HMGB1, inhibiting cytokine activities, thus potentially improving DED.

Aim

To assess the efficacy and tolerance of glycyrrhizin in moderate DED.

Methods

Multicenter, open-label, prospective, nonrandomized clinical pilot study of glycyrrhizin 2.5% eye drops twice daily over 28 days in adult patients with moderate DED using standard evaluation parameters.

Results

The overall mean age of the 37 patients included was 59.6±19.0 years, 70.3% of the patients were female and 77.0% of the patients had an Oxford score of II. After 28 days, 60.8% of the patients had an Oxford score of 0 or I; a significant mean improvement in the score of 0.97±0.86 (P<0.001) from 2.20±0.44 at day 1 to 1.23±0.88 at day 28 was observed. Tear break-up time and Schirmer scores had significantly improved while the number of patient-reported symptoms had significantly decreased (all P≤0.010). A large majority of patients still had a few spots on their naso-bulbar conjunctiva (86.1%), temporal-bulbar conjunctiva (81.4%) and cornea (84.7%). The investigators considered that DED had improved in 71.6% of the patients. Patients appreciated the eye drops for their efficacy and good tolerance profile, leading to a decreased use of artificial tears. No changes in intraocular pressure and visual acuity were observed; glycyrrhizin 2.5% eye drops were safe, with only one patient reporting a moderate, transient treatment-related contact allergy leading to the withdrawal of the patient. Overall, two patients reported three adverse events, two (moderate contact allergy in both eyes) were related to the eye drops and experienced by the same patient; treatment was stopped; the third event was not treatment-related.

Conclusion

In this pilot study, glycyrrhizin 2.5% eye drops were well tolerated and provide a good clinical benefit to patients with moderate DED after 28 days of continued daily use.

Clinical signs of meibomian gland dysfunction (MGD) are associated with changes in meibum sphingolipid composition

PURPOSE

Sphingolipids (SPL) play roles in cell signaling, inflammation, and apoptosis. Changes in SPL composition have been reported in individuals with MGD, but associations between clinical signs of MGD and compositional changes in meibum SPLs have not been examined.

METHODS

Forty-three individuals underwent a tear film assessment. Groups were split into those with good or poor quality meibum. Meibum was collected then analyzed with liquid chromatography-mass spectroscopy to quantify SPL classes. Relative composition of SPL and major classes, Ceramide (Cer), Hexosyl-Ceramide (Hex-Cer), Sphingomyelin (SM), Sphingosine (Sph) and Sphingosine 1-phosphate (S1P) was calculated via mole percent.

RESULTS

22 and 21 individuals were characterized with good and poor quality meibum, respectively. Individuals with poor quality were older (60 ± 8 vs 51 ± 16 years) and more likely to be male (90% vs 64%). Relative composition analysis revealed that individuals with poor meibum quality had SPL composed of less Cer (33.36% vs 49.49%, p < 0.01), Hex-Cer (4.88% vs 9.15%, p < 0.01), and S1P (0.16% vs 0.31%, p = 0.05), and more SM (58.67% vs 38.18%, p < 0.01) and Sph (2.92% vs 2.87%, p = 0.97) compared to individuals with good quality meibum. Assessment of the ratio of Cer (pro-apoptotic) to S1P (pro-survival) showed that individuals with poor meibum quality had a relative increase in Cer (495.23 vs 282.69, p = 0.07).

CONCLUSION

Meibum quality, a clinically graded marker of MGD, is associated with compositional changes in meibum sphingolipids. Further investigation of the structural and bioactive roles of sphingolipids in MGD may provide future targets for therapy.

Neurological and Inflammatory Manifestations in Sjögren's Syndrome: The Role of the Kynurenine Metabolic Pathway

For decades, neurological, psychological, and cognitive alterations, as well as other glandular manifestations (EGM), have been described and are being considered to be part of Sjögren's syndrome (SS). Dry eye and dry mouth are major findings in SS. The lacrimal glands (LG), ocular surface (OS), and salivary glands (SG) are linked to the central nervous system (CNS) at the brainstem and hippocampus. Once compromised, these CNS sites may be responsible for autonomic and functional disturbances that are related to major and EGM in SS. Recent studies have confirmed that the kynurenine metabolic pathway (KP) can be stimulated by interferon-γ (IFN-γ) and other cytokines, activating indoleamine 2,3-dioxygenase (IDO) in SS. This pathway interferes with serotonergic and glutamatergic neurotransmission, mostly in the hippocampus and other structures of the CNS. Therefore, it is plausible that KP induces neurological manifestations and contributes to the discrepancy between symptoms and signs, including manifestations of hyperalgesia and depression in SS patients with weaker signs of sicca, for example. Observations from clinical studies in acquired immune deficiency syndrome (AIDS), graft-versus-host disease, and lupus, as well as from experimental studies, support this hypothesis. However, the obtained results for SS are controversial, as discussed in this study. Therapeutic strategies have been reexamined and new options designed and tested to regulate the KP. In the future, the confirmation and application of this concept may help to elucidate the mosaic of SS manifestations.

[Prevention and treatment of degenerative changes in ocular surface epithelium in patients with dry eye syndrome]

In current understanding of the pathogenesis of xerotic changes of the ocular surface in patients with dry eye syndrome (DES), great importance is given to hyperosmolarity of the tear film, inflammatory process and oxidative stress. By now, no convincing data has been obtained on whether the oxidative stress is primary in relation to the inflammatory process in the ocular surface tissues, or if it is a complication. Furthermore, in the complex treatment of patients with DES, antioxidant therapy has so far received little attention. This problem can be solved with the 'artificial tears' preparation containing cyanocobalamin (vitamin B12), which antioxidant, anti-inflammatory and clinical effectiveness has been convincingly proved in a number of experimental and clinical studies of recent years. Improving the methods of vital diagnostics of xerosis of the ocular surface also enables detection of subclinical changes in epithelium of the cornea and conjunctiva, thus allowing timely prescription of metabolic therapy. One of the promising directions of such treatment is the use of 5% dexpanthenol, which stimulates the processes of reparative regeneration and possesses an anti-inflammatory effect.

Effects of a sea buckthorn oil spray emulsion on dry eye

PURPOSE

To investigate the effects of a sea buckthorn oil and sodium hyaluronate-containing eyelid spray emulsion (SB spray) on dry eye.

METHODS

A randomized controlled study was carried out. Adults (25-70 years) with Ocular Surface Disease Index (OSDI) ≥20 and moderate or severe dryness, burning or grittiness of the eyes were included. In study part one (n = 2), SB spray was used on both closed eyelids four times in one day. In part two (n = 10), SB spray was used on one randomized eyelid, and a commercial reference spray on the other for nine days. In part three (n = 40), eyes were randomized to one eye receiving SB spray and an untreated control for 1.5 months. Dry eye tests were carried out at baseline, during, and at the end of each study section. Symptoms were recorded in questionnaires and daily logs.

RESULTS

In part one, the SB spray was well tolerated. In part two, OSDI decreased significantly (P = 0.022) in the SB spray eye compared to the reference spray, indicating a beneficial effect on symptoms. In part three, OSDI in the SB spray eye decreased significantly compared to the untreated control (P = 0.0007). The scores for dryness at the study end were lower in the SB spray eye compared to control (P = 0.0070). Symptom sums and frequencies of dryness (sum P = 0.0046, frequency P = 0.0016) and watering (sum P = 0.0003, frequency P = 0.013) in the daily logs were lower in the eye treated with SB spray.

CONCLUSIONS

SB spray on closed eyelids relieved the symptoms of dry eye.

Reconsidering the central role of mucins in dry eye and ocular surface diseases

Mucins are key actors in tear film quality and tear film stability. Alteration of membrane-bound mucin expression on corneal and conjunctival epithelial cells and/or gel-forming mucin secretion by goblet cells (GCs) promotes in ocular surface diseases and dry eye disease (DED). Changes in the mucin layer may lead to enhanced tear evaporation eventually contributing to tear hyperosmolarity which has been associated with ocular surface inflammation. Inflammatory mediators in turn may have a negative impact on GCs differentiation, proliferation, and mucin secretion. This sheds new light on the position of GCs in the vicious circle of DED. As contributor to ocular surface immune homeostasis, GC loss may contribute to impaired ocular surface immune tolerance observed in DED. In spite of this, there are no tools in routine clinical practice for exploring ocular surface mucin deficiency/dysregulation. Therefore, when selecting the most appropriate treatment options, there is a clear unmet need for a better understanding of the importance of mucins and options for their replacement. Here, we comprehensively revisited the current knowledge on ocular surface mucin biology, including functions, synthesis, and secretion as well as the available diagnostic tools and treatment options to improve mucin-associated homeostasis. In particular, we detailed the potential link between mucin dysfunction and inflammation as part of the uncontrolled chronic inflammation which perpetuates the vicious circle in DED.

The role of endocrine disruptors in ocular surface diseases

Endocrine disruptors are a group of compounds that occur in increasing amounts in the environment. These compounds change the hormone homeostasis of the target organs regulated by those hormones, mostly by binding to their receptors and affecting their signaling pathways. Among the hormones altered by endocrine disruptors are sex hormones, thyroid hormones, and insulin. Studies have documented abnormalities in the reproductive and metabolic systems of various animal species exposed to endocrine disruptors. Endocrine disruptors can play a significant role in ocular diseases once hormone deficiency or excess are involved in the mechanism of that disease. Cataracts, dry eye disease and retinal diseases, such as macular hole and diabetic retinopathy, are some of the frequent problems where hormones have been implicated. We found that some compounds function as endocrine disruptors in the metabolism of body organs and systems. The increasing frequency of dry eye and other ocular diseases indicates the need to better investigate the potential relationships beyond the isolated associations mentioned by patients and documented as rare case reports. The evidence from case-control studies and experimental assays can provide the information necessary to confirm the endocrine effects of these chemicals in the pathophysiology of dry eye disease. We hypothesize that endocrine disruptors may contribute to the increase of ocular diseases, such as dry eye disease, in recent years.

TRPM8 Channels and Dry Eye

Transient receptor potential (TRP) channels transduce signals of chemical irritation and temperature change from the ocular surface to the brain. Dry eye disease (DED) is a multifactorial disorder wherein the eyes react to trivial stimuli with abnormal sensations, such as dryness, blurring, presence of foreign body, discomfort, irritation, and pain. There is increasing evidence of TRP channel dysfunction (i.e., TRPV1 and TRPM8) in DED pathophysiology. Here, we review some of this literature and discuss one strategy on how to manage DED using a TRPM8 agonist.

Interferons and Dry Eye in Sjögren's Syndrome

Various cytokines, including interferon (IFN)-γ and IL-17, are augmented, and autoreactive T cells and B cells are activated in the immune pathogenesis of Sjögren's syndrome (SS). In particular, IFNs are involved in both the early stages of innate immunity by high level of type I IFN in glandular tissue and sera and the later stages of disease progression by type I and type II IFN producing T cells and B cells through B cell activating factor in SS. Genetically modified mouse models for some of these molecules have been reported and will be discussed in this review. New findings from human SS and animal models of SS have elucidated some of the mechanisms underlying SS-related dry eye. We will discuss IFN-γ and several other molecules that represent candidate targets for treating inflammation in SS-related dry eye.

Neurostimulation in dry eye disease-past, present, and future

Neuromodulation is a novel approach that utilizes electrical signals, pharmaceutical agents, or other forms of energy to modulate abnormal neural function through neurostimulation. Neurostimulation is a novel technique that uses electrical currents to stimulate the nervous system. During the recent few decades, neuromodulation has gained significant attention, in particular for the treatment of chronic neurological diseases, due to its success in treating patients unresponsive to conventional pharmacological therapies. Dry eye disease (DED) is a chronic, multifactorial disease that affects millions of people worldwide. Recent data have demonstrated that neurosensory abnormalities contribute to the pathogenesis of DED. Current mainstays of dry eye therapy include lubrication, tear retention, and anti-inflammatory therapies, among others. The recent development of intranasal neurostimulation therapy for DED utilizes the nasolacrimal reflex as an alternative pathway, not only to increase tear production via increased lacrimation, but also to target other tear film components, such as mucin and meibum secretion, promoting tear film homeostasis. This review aims to describe the different types of neuromodulation devices available and their application for non-ocular diseases, as well as to review recent advances and literature on ocular neurostimulation.

Effect of Single Instillation of Two Hyaluronic Acid-Based Topical Lubricants on Tear Film Thickness in Patients with Dry Eye Syndrome

PURPOSE

This study investigated the effect of single administration of 2 different hyaluronic acid-based topical lubricants on tear film thickness (TFT) in patients with moderate-to-severe dry eye disease (DED).

METHODS

Sixty patients were randomized to receive eye drops containing unpreserved sodium hyaluronate, triglycerides, and phospholipids (HTP), unpreserved sodium hyaluronate (HA), or unpreserved sodium chloride (NaCl). TFT and lipid layer thickness (LLT) were assessed before and at defined time points after single instillation with a custom-built ultrahigh-resolution optical coherence tomography system and a white light interferometer. Standard tests for DED such as a visual analogue scale (VAS), corneal fluorescein staining (CFS), Schirmer I test, and tear break-up time (BUT) were performed.

RESULTS

The time course in TFT was significantly different between the 3 administered agents (P < 0.001). Single administration of HTP significantly increased TFT over a period of 40 min, an increase in TFT over 20 min was observed after instillation of HA, whereas NaCl had no effect. No significant difference in the change in BUT, CFS, or LLT was observed between the 3 groups (P = 0.57, 0.97, and 0.86, respectively). A significant improvement in subjective symptoms (VAS) was found after single instillation of HTP (P = 0.03 vs. baseline) and HA, but not after administration of NaCl (P = 0.03, P < 0.01, and P = 0.08 vs. baseline, respectively, P = 0.57 between groups).

CONCLUSIONS

Single administration of HTP and HA significantly increased TFT showing a longer residence time and improved subjective symptoms, whereas instillation of NaCl had no effect. Long-term studies with multiple instillations will be necessary to further investigate the effect of the tested products on the clinical outcome. ClinicalTrials.gov ID: NCT03161080.

Safety and Tolerability of Overdosed Artificial Tears by Abraded Rabbit Corneas

Purpose: Preservative-free cationic emulsion-based artificial tear (AT) is an innovative eye drop based on the Novasorb^® technology with cetalkonium chloride (CKC) as the cationic agent. The cationic emulsion Cationorm is designed for the management of mild-to-moderate dry eye disease (DED) patients that present cornea epithelium alterations. The aim of the present study was to evaluate the safety and tolerability of overdosed ATs by altered corneal epithelium in vivo and assess the usefulness of the ex vivo eye irritation test (EVEIT) as a predictive alternate toxicity test method.

Methods: The experimental procedure, treatment duration, and instillation frequency closely mimic in vivo the ex vivo protocol described by Pinheiro et al. and discussed in the Discussion and Conclusion section of this article. Two to 3-month-old female New Zealand white rabbits, n = 6 per group, were treated with ATs (21 instillations/day over 3 days) following corneal abrasion. Corneal fluorescein staining, in vivo confocal microscopy (IVCM), and slit lamp examinations were performed to assess corneal epithelium recovery and the ocular tolerability of the overdosed ATs.

Results: All abraded eyes experienced almost complete epithelium recovery within 3 days following treatments with Cationorm, Optive, Vismed, and Saline. Benzalkonium chloride (BAK, 0.02%) treatment resulted in 82.4% reepithelialization. IVCM data illustrated corneal epithelium normal recovery. Acute local tolerability of the overdosed ATs was confirmed using Draize and McDonald–Shadduck's test scales.

Conclusions: The different ATs were demonstrated to be well tolerated by abraded corneas in vivo, and the extreme overdosing regimen did not hamper the wound healing process of the rabbit eye in comparison to saline. These data did not confirm the ones obtained with the nonvalidated ex vivo eye irritation test.

Once-Daily Cyclosporine-A-MiDROPS for Treatment of Dry Eye Disease

Purpose

To determine if a Microemulsion Drug Ocular Penetration System (MiDROPS) formulation of cyclosporine A (CsA) delivers more drug and is more efficacious for treatment of dry eye disease (DED) than the current clinical formulation.

Methods

Tissue distribution of CsA was quantified by liquid chromatography with tandem mass spectrometry (LC-MS/MS). To assess tolerability, CsA-MiDROPS (0.1%) was applied to the eyes of rabbits twice per day for 14 days and assessed using ophthalmoscopic examinations. Mice were exposed to desiccating stress for 10 days and received daily topical instillation of the vehicle or test agent. Cornea staining was done to quantify corneal permeability. Histologic quantification of goblet cell (GC) density and CD4⁺ T-cell infiltration in the conjunctiva was performed.

Results

Ophthalmic distribution studies indicate significantly increased drug concentration with CsA-MiDROPS compared with Restasis. CsA-MiDROPS is well tolerated with little toxicity in a 2-week tolerability study. In the DED model, both 0.05% and 0.1% CsA-MiDROPS conferred a significant effect and were more effective than Restasis for treating experimental DED when dosed twice per day. As compared with Restasis dosed twice per day, 0.1% CsA-MiDROPS dosed once per day demonstrated superiority.

Conclusions

CsA-MiDROPS showed superior drug delivery and efficacy compared with other clinical formulations. As this product is simple to produce and needs to be only applied once daily, the clinical development of CsA-MiDROPS will help to reduce societal and patient burdens by lowering drug costs and accelerating/improving the activity of CsA.

Translational Relevance

MiDROPS has broad application concerning the ophthalmic development of lipophilic small molecule therapeutics.

A Phase II/III, randomized, double-masked, vehicle-controlled, dose-ranging study of the safety and efficacy of OTX-101 in the treatment of dry eye disease

Purpose

The aim of this study was to evaluate the safety and efficacy of OTX-101, a clear nanomicellar aqueous solution of cyclosporine, in the treatment of dry eye disease (DED).

Patients and methods

This was a 12-week multicenter, randomized, prospective, double-masked, vehicle-controlled, dose-ranging clinical trial. Subjects were adults aged ≥18 years, with a total conjunctival staining score of ≥3 and ≤9, and global DED symptom score ≥40 (0–100 visual analogue scale). Following a 14-day vehicle run-in, subjects were randomized in a 1:1:1 ratio to twice daily treatment with OTX-101 0.09%, OTX-101 0.05%, or vehicle for 84 days. Co-primary efficacy end points were changes, from baseline to Day 84, in the total lissamine green conjunctival staining score in the designated study eye and in the global symptom score (both eyes). Secondary end points included total corneal fluorescein staining score, tear breakup time, and Schirmer’s test score.

Results

In total, 455 subjects were randomized. Subjects treated with active drug experienced greater improvement in conjunctival staining than vehicle-treated patients (P<0.01 for both concentrations). All groups demonstrated improvements in global symptom score, but there were no differences among groups. Nominally significant differences were found between the active drug arms and vehicle for corneal staining scores and Schirmer’s test scores. Most treatment-emergent adverse events were mild in severity; no serious ocular adverse events were reported.

Conclusions

Both concentrations of OTX-101 met the co-primary sign end point (conjunctival staining) but not the co-primary symptom end point. OTX-101 0.09% demonstrated a notable impact on multiple signs of DED relative to vehicle and was well-tolerated.

Blue light phototoxicity toward human corneal and conjunctival epithelial cells in basal and hyperosmolar conditions

AIMS

The ocular surface is the very first barrier between the visual system and external environment. It protects the eye from the exposure to various light sources that significantly emit in blue spectrum. However, the impact of blue light on the ocular surface has been poorly explored so far. In this study, we investigated in vitro the phototoxicity of blue light illumination in human epithelial cells of the ocular surface. We worked either in basal conditions or under hyperosmolar stress, in order to mimic dry eye disease (DED) that is the most common disease involving the ocular surface.

RESULTS

Corneal and conjunctival epithelial cells suffered the most from violet-blue light but also from longer-wave blue light. Exposure to blue wavebands significantly decreased cellular viability, impacted on cellular morphology and provoked reactive oxygen species (ROS) over-production. Conjunctival epithelial cell line had a greater photosensitivity than the corneal epithelial one. Hyperosmolar stress potentiated the blue light phototoxicity, increasing inflammation, altering mitochondrial membrane potential, and triggering the glutathione-based antioxidant system.

INNOVATION

In human epithelial corneal and conjunctival cells of the ocular surface, we demonstrated the harmful impact of blue light on viability, redox state and inflammation processes, which was modified by hyperosmolarity.

CONCLUSION

Blue light induced cell death and significant ROS production, and altered the expression of inflammatory genes and operation of the cellular defensive system. We established for the first time that hyperosmolar stress impacted phototoxicity, further suggesting that DED patients might be more sensitive to blue light ocular toxicity.

Dry Eye Disease in Routine Rheumatology Practice

Dry eye disease (DED) is one of the most frequent ophthalmological conditions, with a major impact on patients’ quality of life. Tear film instability and tear hyperosmolarity are considered to play a crucial role in the vicious cycle of dry eye disease. They occur as a result of, either a reduced lacrimal secretion or an excessive evaporation from the tear film. There is a well-known association of DED, not only with autoimmune diseases but also with other systemic diseases and medication. Early diagnosis is important and it is based on the presence of classical symptoms and signs of dry eye in combination with specialized methods. The comprehension of the pathophysiology is significant, as different approaches can be taken to treat DED, depending on the cause and primary source of the disease, as well as on disease severity.

Immune Response Targeting Sjögren's Syndrome Antigen Ro52 Suppresses Tear Production in Female Mice

Autoantibodies reactive against Ro52 are present in 70% of Sjögren’s syndrome patients and are associated with higher disease severity. However, their role in causing aqueous deficient dry eye, a major cause for morbidity in Sjögren’s syndrome, is unclear. To investigate whether immune responses targeting Ro52 contribute towards the dry eye, male and female NZM2758 mice were immunized with recombinant Ro52. Tear production was measured by the phenol red thread test. Sera were analyzed for anti-Ro52 levels by immunoprecipitation. Lacrimal glands were evaluated for inflammatory foci and IgG deposits. Our results showed that, although all mice generated anti-Ro52 antibodies, only females developed a significant drop in tear production. None of the mice developed severe lacrimal gland inflammation, and female mice with anti-Ro52 showed higher levels of IgG deposits within their glands. Passive transfer of anti-Ro52 sera caused reduced tear production in female mice, but not in males. This study demonstrates for the first time that immune responses initiated by Ro52 induce aqueous dry eye, and this may be driven by anti-Ro52 antibodies. Furthermore, the sexual dimorphism in glandular dysfunction suggests that the lacrimal glands in females are more susceptible to autoantibody-mediated injury.

Biomarkers for Progenitor and Differentiated Epithelial Cells in the Human Meibomian Gland

The meibomian gland (MG) is a sebaceous gland that secretes through a holocrine process. Because such secretion requires the destruction of MG acinar epithelial cells, they need constant renewal and differentiation. The processes that promote these regenerative events in the human MG are unknown, nor is it known how to distinguish MG progenitor and differentiated cells. We discovered that Lrig1 and DNase2 serve as biomarkers for human MG progenitor and differentiated cells, respectively. Lrig1 is expressed in MG basal epithelial cells in the acinar periphery, a location where progenitor cells originate in sebaceous glands. DNase2 is expressed in the differentiated epithelial cells of the MG central acinus. Furthermore, proliferation stimulates, and differentiation suppresses, Lrig1 expression in human MG epithelial cells. The opposite is true for DNase2 expression. Our biomarker identification may have significant value in clinical efforts to restore MG function and to regenerate MGs after disease‐induced dropout. Stem Cells Translational Medicine2018;7:887–892

Ethnic differences between the Asian and Caucasian ocular surface: A co-located adult migrant population cohort study

PURPOSE

To investigate the ethnic differences in tear film quality, ocular surface parameters, and dry eye symptomology between co-located Asian and Caucasian populations.

METHODS

Two hundred and six participants (103 East Asian and 103 Caucasian) were recruited in an age and gender-matched cross-sectional study. Dry eye symptomology, ocular surface parameters, and tear film quality were evaluated for each participant within a single clinical session.

RESULTS

The mean ± SD age of the 206 participants (82 male, 124 female) was 45 ± 16 years. Overall, a greater proportion of Asian participants were symptomatic of dry eye and fulfilled the TFOS DEWS II dry eye diagnostic criteria than Caucasian participants (74% versus 51%, p = 0.002), with an odds ratio (95% CI) of 2.7 (1.5-4.8) times. Poorer OSDI scores, tear film stability, lipid layer quality, tear osmolarity, lid wiper epitheliopathy, meibomian gland dropout, and expressed meibum quality were observed in the Asian group (all p < 0.05). A significantly higher proportion of participants exhibited incomplete blinking in the Asian group than the Caucasian group (81% versus 45%, p < 0.001).

CONCLUSIONS

Asian participants exhibited more severe dry eye signs and symptoms than Caucasian participants. The poorer meibomian gland function and higher degree of incomplete blinking observed among Asian participants may potentially contribute towards the ethnic predisposition towards dry eye development.

Exploring the Asian ethnic predisposition to dry eye disease in a pediatric population

PURPOSE

To investigate the differences in ocular surface characteristics, tear film parameters, and dry eye symptomology between co-located pediatric populations of Asian and Caucasian ethnicity.

METHODS

Seventy New Zealand-born pediatric participants, aged between 5 and 18 years, were recruited in an age and environmentally controlled cross-sectional study. Participants were classified into three groups according to ethnicity and eyelid morphology: Asian single lid (ASL), Asian double lid (ADL), and Caucasian double lid (CDL). Ocular biometry, tear film parameters, ocular surface characteristics, and dry eye symptomology were evaluated in a single clinical session.

RESULTS

Overall, no significant intergroup differences were observed in tear film quality, dry eye symptomology, and meibomian gland dropout. A higher proportion of ASL and ADL participants exhibited incomplete blinking than the Caucasian group (both p < 0.001). Meibomian gland shortening was more frequently observed among the two Asian groups (both p < 0.05), while gland tortuosity was more common in the Caucasian group (both p < 0.001). ASL participants exhibited greater inferior lid wiper epitheliopathy grades than ADL participants (p = 0.01), and corneal astigmatism was more pronounced in the ASL than CDL group (p = 0.02).

CONCLUSIONS

Ethnic differences in meibomian gland morphological patterns were observed in the current pediatric cohort, although overall meibomian gland dropout did not differ between groups. Asian participants exhibited a higher degree of incomplete blinking, and more marked inferior lid wiper epitheliopathy and corneal astigmatism were observed in the ASL group. These findings would suggest that eyelid anatomy and tension may potentially be implicated in the development of ethnic differences in dry eye disease later in life.

Assessment of Ocular Surface Damage during the Course of Type 2 Diabetes Mellitus

Purpose

To investigate the impact of disease duration on the ocular surface during the course of type 2 diabetes mellitus compared with nondiabetic controls.

Methods

One hundred twenty diabetic patients were divided into three groups according to disease duration: less than 5 years, 5–10 years, and over 10 years. All eyes were imaged using a corneal topographer (Oculus Keratograph 5M). Tear film measurements and meibography were also recorded. Meibomian gland changes were scored from 0 to 6 (meiboscore).

Results

The noninvasive breakup time first (NIKBUT-1st) and noninvasive breakup time average (NIKBUT-avg) were significantly shorter in the over 10 years diabetic group compared with the control group (P=0.0056  and  P=0.010, resp.). Tear meniscus height (TMH) was significantly lower in the over 10 years diabetic group compared with the control group (P=0.0016) and the 5 years group (P=0.0061). We also found that more patients in the over 10 years diabetic group showed bulbar and limbal hyperemia compared with the control group (bulbar hyperemia: P=0.049; limbal hyperemia: P=0.026). The meiboscore in the over 10 years diabetic group was significantly higher compared with the other three groups (P < 0.05). Bulbar hyperemia showed a significant negative correlation with NIKBUT-1st in the over 10 years diabetic group (r=−0.35  and  P < 0.05).

Conclusion

Ocular surface damage in long-term type 2 diabetes is more severe than that in patients with shorter disease duration.

Innate and Adaptive Cell Populations Driving Inflammation in Dry Eye Disease

Dry eye disease (DED) is the most common ocular disease and affects millions of individuals worldwide. DED encompasses a heterogeneous group of diseases that can be generally divided into two forms including aqueous-deficient and evaporative DED. Evidence suggests that these conditions arise from either failure of lacrimal gland secretion or low tear film quality. In its secondary form, DED is often associated with autoimmune diseases such as Sjögren's syndrome and rheumatoid arthritis. Current treatment strategies for DED are limited to anti-inflammatory medications that target the immune system as the source of deleterious inflammation and tissue injury. However, there is a lack of understanding of the underlying pathogenesis of DED, and subsequently, there are very few effective treatment strategies. The gap in our knowledge of the etiology of primary DED is in part because the majority of research in DED focused on secondary autoimmune causes. This review focuses on what is currently understood about the contribution of innate and adaptive immune cell populations in the pathogenesis of DED and highlights the need to continue investigating the central role of immunity driving DED.

Topical Quercetin and Resveratrol Protect the Ocular Surface in Experimental Dry Eye Disease

Purpose: To determine the anti-inflammatory effect of quercetin (QCT), resveratrol (RES), and their combination in a dry eye disease (DED) model. Methods: 0.01% QCT, 0.1% RES, 0.01% QCT + 0.1% RES (QCT + RES) or vehicle were topically applied in a desiccating stress (DS) mice model. CD4⁺ T cells isolated from DS-exposed mice were transferred to athymic recipient mice. Corneal fluorescein staining, tear production, and tear cytokine levels were evaluated in DS-exposed mice, and conjunctival CD4⁺ T cell infiltration was evaluated in recipient mice. Results: QCT (p < 0.001) and QCT + RES (p < 0.05) reduced corneal staining in DS-exposed mice. IL-1α tear concentration was reduced by QCT, RES, and QCT + RES (p < 0.05, 0.01 and 0.01, respectively) compared to DS + vehicle mice. CD4⁺ T cells increased in recipients of DS-exposed mice (p < 0.05) and were lower in recipients of QCT- and RES-treated mice (p < 0.05). Conclusion: The anti-inflammatory effect of QCT, RES, and QCT + RES on DED-experimental model suggests that their topical application could be used for DED treatment.

Dry Eye Assessment and Management (DREAM©) Study: Study design and baseline characteristics

PURPOSE

Describe trial design and baseline characteristics of participants in the DRy Eye Assessment and Management (DREAM©) Study.

DESIGN

Prospective, multi-center, randomized, double-masked "real-world" clinical trial assessing efficacy and safety of oral omega-3 (ω3) supplementation for the treatment of dry eye disease (DED).

METHODS

RESULTS: Mean age of participants was 58.0 ± 13.2 years. Mean OSDI score at baseline was 44.4 ± 14.2. Mean conjunctival staining score (scale 0-6) was 3.0 ± 1.4, corneal staining score (scale 0-15) was 3.9 ± 2.7, tear break-up time was 3.1 ± 1.5 s, and Schirmer test was 9.6 ± 6.5 mm/5 min.

CONCLUSIONS

DREAM© participants mirror real world patients who seek intervention for their DED-related symptoms despite their current treatments. Results regarding the efficacy of omega-3 supplementation will be helpful to clinicians and patients with moderate to severe DED who are considering omega-3 as a treatment. This trial design may be a model for future RCT's on nutritional supplements and DED treatments seeking to provide useful information for clinical practice.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT02128763.

The immunoregulatory role of corneal epithelium-derived thrombospondin-1 in dry eye disease

PURPOSE

In this study, we examine the expression of corneal epithelium-derived thrombospondin-1 (TSP-1) and its immunomodulatory functions in a validated murine model of dry eye disease (DED).

METHODS

DED was induced in female C57BL/6 using a controlled environment chamber (CEC) for 14 days. mRNA and protein expression of TSP-1 by corneal epithelial cells was quantified using real-time PCR and flow cytometry. Corneal epithelial cells from either naïve or DED mice were cultured with bone marrow derived dendritic cells (BMDCs) in the presence of IFNγ for 48 h, and BMDC expression of MHC-II and CD86 was determined using flow cytometry. Next, either recombinant TSP-1 or anti-TSP-1 antibody was added to the co-culture, and BMDC expression of above activation markers was evaluated. Finally, either DED mice were topically treated with either recombinant TSP-1 or human serum albumin (HSA), and maturation of corneal DCs, expression of inflammatory cytokines, and DED severity were investigated.

RESULTS

mRNA expression of TSP-1 by the corneal epithelium was upregulated in DED. Corneal epithelial cells derived from mice with DED demonstrated an enhanced capacity in suppressing BMDC expression of MHC-II and CD86 relative to wild type mice, and this effect was abrogated by TSP-1 blockade and potentiated by recombinant TSP-1. Finally, topical application of recombinant TSP-1 significantly suppressed corneal DC maturation and mRNA expression of pro-inflammatory cytokines, and ameliorated disease severity in mice with DED.

CONCLUSIONS

Our study elucidates the function of epithelium-derived TSP-1 in inhibiting DC maturation and shows its translational potential to limit corneal epitheliopathy in DED.

Conjunctival MUC5AC+ goblet cell index: relationship with corneal nerves and dry eye

PURPOSE

To evaluate the relative proportion of conjunctival MUC5AC+ and MUC5AC- goblet cells in a post-LASIK population and their association with dry eye indicators and corneal nerve morphology using a MUC5AC+ Goblet Cell Index.

METHODS

Twenty subjects who had undergone LASIK > 12 months previously and 20 age-matched controls were recruited. Dry eye symptoms, tear breakup time, osmolarity, meniscus area and corneal nerve morphology were examined. Conjunctival impression cytology samples were collected from inferior-temporal bulbar conjunctiva using Millicell® inserts. Total goblet cell density was determined from positive cytokeratin-7 (CK7) immunolabelling; MUC5AC+ goblet cell density was determined from both CK7+- and MUC5AC+-immunolabelled cells. The ratio of MUC5AC+ to total density was defined as the "MUC5AC+ Goblet Cell Index". Differences in variables between groups and the associations between goblet cell variables and clinical assessments were examined.

RESULTS

No significant differences in the total and MUC5AC+ goblet cell density and tear film parameters were found between groups, although greater ocular discomfort was reported in the post-LASIK group (P = 0.02). A higher MUC5AC+ Index was associated with worse/greater dry eye symptoms (ρ = 0.55, P = 0.01) and higher nerve tortuosity (ρ = 0.57, P = 0.01) in the post-LASIK group; lower nerve density and thickness was found in controls (ρ > -0.45, P < 0.05), but not associated with tear film parameters.

CONCLUSIONS

The MUC5AC+ Goblet Cell Index provides an indicator of mucin secretion for assessing the goblet cell function in dry eye. In the post-LASIK participants, we found an increased MUC5AC+ Index associated with worse dry eye symptoms and adverse changes in corneal nerve morphology.

Comparison of 0.1%, 0.18%, and 0.3% Hyaluronic Acid Eye Drops in the Treatment of Experimental Dry Eye

PURPOSE

To compare the efficacy of 0.1%, 0.18%, and 0.3% hyaluronic acid (HA) artificial tear in the treatment of experimental dry eye (EDE).

METHODS

EDE was established in female C57BL/6 mice through an air draft and subcutaneous scopolamine injection. The mice were divided into 5 groups according to topical treatment regimens (n = 5 each): EDE control, balanced salt solution (BSS), preservative-free 0.1% HA, 0.18% HA, and 0.3% HA. The tear film break-up time (TBUT) and corneal fluorescein staining scores were measured 5, 10, 14, 21, and 28 days after treatment. The corneal smoothness scores were measured. In addition, periodic acid-Schiff (PAS) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were performed.

RESULTS

The values for TBUT and corneal fluorescein staining showed greater improvements in all the HA groups (P < 0.05) than in the EDE and BSS groups after 10 days of treatment. Mice treated with 0.3% HA showed a more significant improvement in all clinical parameters than did those in the EDE control, BSS, 0.1% HA, and 0.18% HA groups (all P < 0.05) after 28 days of treatment. The goblet cell counts were higher in the 0.3% and 0.18% HA groups than in the 0.1% HA group. The number of TUNEL-positive cells was the lowest in the 0.3% HA group.

CONCLUSIONS

In EDE, 0.3% HA artificial tears are more effective than the 0.1% and 0.18% HA in improving tear film instability and ocular surface staining and irregularity, in increasing the number of conjunctival goblet cells, and in decreasing corneal epithelial apoptosis.